M/F ratios of four different closing loops: 3D analysis using the finite element method (FEM).

Background: It has been claimed that the opus loop is capable of delivering a constant and optimum M/F ratio without the need for gable bends.

Objective: To compare the forces, moments and moment/force (M/F) ratios of the opus loop, L-loop, T-loop and vertical helical closing loop (VHC loop) in a segmented arch with the finite element method (FEM).

Methods: The FEM was used to compare 3D models of closing loops in rectangular (0.